1. Field of the Invention
The present invention relates to an organic electroluminescent display, and more particularly to an organic electroluminescent display with an improved encapsulation structure.
2. Description of the Related Art
Generally, organic electroluminescent displays are self emission displays that emit light by electrically exciting a fluorescent organic compound. Organic electroluminescent displays can be advantageous over liquid crystal displays (LCDs) because organic electroluminescent displays require low driving voltage, easy thin film formation, provide wide viewing angle, and have fast response speed. Therefore, there has been an increasing interest in organic electroluminescent displays as the next generation of displays.
The organic electroluminescent displays include a substrate and an organic light-emitting unit having a sequentially stacked structure of a first electrode, an organic film, and a second electrode on the substrate. The organic electroluminescent displays may include an encapsulation cover bonded to the substrate to seal a space containing the organic light-emitting unit.
In such organic electroluminescent displays, when positive and negative voltages are applied to these electrodes, holes from the positive voltage-applied electrode migrate toward the light-emitting layer of the organic film via a hole transport layer and electrons from the negative voltage-applied electrode are injected into the light-emitting layer via an electron transport layer. At this time, the electrons and the holes recombine with each other in the light-emitting layer to generate an exciton. When the exciton is changed from an excited state to a ground state, a fluorescent molecule of the light-emitting layer emits light, thereby displaying an image.
However, such organic electroluminescent displays last only so long because the organic film is very susceptible to moisture and oxygen. That is, moisture and oxygen decrease the life span of the organic film as well as deteriorate the characteristics of the organic film. In this regard, it is necessary to prevent moisture and oxygen from ever coming into contact with the organic film. Therefore, what is needed is a design for an organic electroluminescent display that better prevents moisture and oxygen from ever contacting the organic layer.